In order to supply an electrical load through a galvanic isolation barrier, it is known to use an isolated power supply comprising a transformer. The transformer comprises a primary connected to its terminals with a voltage source and a secondary connected to the electrical load. In this known power supply, the purpose of an output capacitor connected to the terminals of the secondary is to store electrical energy and accordingly has a very large value, generally more than a microfarad.
In particular an isolated resonant power supply is known which uses a resonance between a capacitor and an inductor for zero voltage switching or ZVS of a switch belonging to the power supply. The document ‘A novel resonant converter topology for DC-to-DC power supply’ by Liu et al. published in ‘IEEE Transactions on Aerospace and Electronic Systems’, Vol. 31, No 4, October 1995, 1301, discloses an example of a resonant power supply. One problem of resonant power supplies is that their output voltage may depend on the impedance of the electrical load supplied by the power supply.
The present invention is therefore aimed at obtaining an isolated resonant power supply in which the output voltage is independent of the impedance of the load at the output of the power supply.